Random threshold mismatches in an array of addressable MOSFETs have been recently used to identify integrated circuits (ICs). The technique leverages on process discrepancies unavoidably formed during fabrication. This technique can also be used for authentication, intellectual property (IP) tagging, and other applications.
Computational security has been the traditional field of study for IP management. IP protection such as software and hardware usage metering are among the problems studied in this field. Cryptography is the practice and study of hiding information and until recently it referred almost exclusively to encryption, such as confidentiality and data integrity. Computational security has an even more broad scope and includes privacy protection, password protection, denial of service, and content usage measuring. IP protection of audio and video artifacts and hardware and software components and systems has gained attention throughout the past few years. The two main methods for measuring the popularity of media channels are sampling and auditing. Sampling may be based on surveys among a representative group of users.
Web page access metering has been addressed by a number of researchers and companies. Techniques have been proposed to uniquely identify users and to compensate for the usage of proxies and caches. Mechanisms for metering the popularity of web-sites have been proposed. Some schemes measure the amount of service requested from servers by clients. Licensing has been the most popular method used for software protection among vendors. Licensing software ensures the vendor with a certain degree of control over the distributed software. For example, licensing software may prevent unauthorized duplication of software packages and licensing is a major enabling component for software distribution.
Currently, the dominating software licensing mechanism is based on the license key concept. A key may be encrypted by using a string of data that contains e.g., a software package identification (ID), its usage constraints (e.g., expiration date), and so forth. The invocation of the software package is done automatically when the appropriate key is provided. A large number of licensing protocols have been proposed. Some involves the using of smart cards.